Stand for helical rolling



1968 F, P. KIRPICHNIKOV ETAL 3,415,090

STAND FOR HELICAL ROLLING Filed Dec. 15, 1965 2 Sheets-Sheet l FIG./

1968 F. P. KIRPICHNIKOV ETAL 3,415,090

STAND FOR HELICAL ROLLING Filed Dec 15, 1965 2 Sheets-Sheet M/LL/AMMEI' 1 17677! sews/N6 aw/r 3.9

United States Patent 3,415,090 STAND FOR HELICAL ROLLING Felix Petrovich Kirpichnikov, Leninsky prospekt 32, kv. 18; Viktor Ivanovich Bykasov, Ryazanskoe chaussee 17, kv. 41; Leonid Nikolaevich Reshetov, 13 Parkovaya ulitsa 25, korpus 1, kv. 56; and Serafim Porfirievich Miljutin, Novye Kuzminki, 116 kvartal, korpus 10, kv. 87, all of Moscow, U.S.S.R.

Filed Dec. 15, 1965, Ser. No. 514,001 4 Claims. (Cl. 72-100) ABSTRACT OF THE DISCLOSURE A working stand which comprises a driven rotary head on which are mounted carriages supporting driven grooved rolls, the head and rolls being driven by respective driving components of an epicyclic gear system, the driving components being driven with a constant relationship of torque in opposite directions.

The present invention relates to the manufacture of riffled tubes by rolling, and more specifically to stands of mills used for the helical rolling of parts in the form of solids of revolution such as rifiled tubes.

It is customary to roll rifiled tubes between three shaped driven rolls disposed around the stock and mounted on the carriages of a stationary working stand. The axes of the rolls interest the axis of the billet at a certain angle referred to as a feed angle. Rotation of the rolls causes the billet, which is plain tubing, to be drawn inward, thus imparting to the billet a rotational and an axial motion in the process of which rifiles are formed.

Rolling of tubes of considerable length gives rise to appreciable difficulties originating from the rotation of the billet. This rotation may be possibly obviated by rolling the tube with aid of a rotary head equipped with backup rolls freely mounted on their shafts, the head in question being similar to those employed in thread rolling. This method is, however, deficient in that the billet is liable to break under the torsional stress due to the torque applied.

This invention has for its object to devise, for the purpose of helical rolling of billets shaped as solids of revolution, for example, rifiled tubes, a stand which is, being simple in construction and dependable in operation, and which precludes rotation and twisting of the billets being rolled.

According to the present invention, there is provided a stand for helical rolling comprising a head carrying rolls, said head and rolls being driven through an epicyclic gear system, the two driving components of which are driven with a constant relation of torque in opposite directions in order to prevent rotation and twisting of the billet being rolled.

The epicyclic gear system can be driven from either two electric motors equipped with a current regulator, or an electric motor with an auxiliary epicyclic differential and two gear trains.

The current regulator intended for use with two motors as mentioned above is some type of amplifier, for example, a magnetic amplifier, provided with a compensator which is designed to compensate for the frictional losses in the drive and comprises controllable sources of direct current to compensate for the losses due to idling of the motors and voltage dividers to compensate for the frictional losses due to operation of the motors under load. Adjustment of the compensator is effected by varying the voltage of the respective direct current source with reference to zero readings of milliammeters inserted in the comparison circuit of the regulator.

To provide for manufacture of "tubes with alternate rifiled and plain portions, the rolls are mounted in the stand head so as to permit their radial movement during the rolling process. Control of roll expansion is effected by a length sensing unit which is essentially a counter registering the number of head revolutions.

In the following description reference is made to the accompanying drawings, wherein:

FIG. 1 illustrates an embodiment of the proposed stand according to which the drive is effected from two electric motors.

FIG. 2 illustrates an embodiment of the proposed stand according to which the drive is effected from two electric motors through an auxiliary epicyclic gear.

FIG. 3 illustrates the control circuit of the electric motors shown in FIGS. 1 and 2.

FIG. 4 illustrates an embodiment of the proposed stand according to which the drive is effected from an electric motor and an epicyclic differential.

The working stand (FIG. 1) is essentially composed of a rotary head 1 with three grooved driven rolls 2 spaced degrees apart and equidistant from the axis of rotation of the head.

The billet 3 is admitted to the rolls through an opening centrally located in the head. The axis of said opening coincides with the axis of rotation of the head and the axis of rolling.

The axes of the rolls 2 intersect the axis of rotation of the head at a small angle, of not more than 6-8 degrees.

The rolls 2 are mounted on the head 1 so that they can be moved radially by means of a pressure mechanism, for example wedges 4 driven from an electric motor or by means of either a pneumatic or a hydraulic cylinder (the mechanism effecting the movement of the wedges 4 is not shown in the drawings).

The action of the springs 5 constantly forces the rolls 2 against the wedges 4.

The head and the rolls are driven from two DC. motors through an epicyclic gear system in such a manner that the head 1 is connected with the planet carrier, whereas the rolls 2 are connected to the planet wheels which receive their motion fro-m the sun wheel. The planet carrier is driven by the motor 6 through gears 7 and 8. The rolls 2 are connected through universal joints 9 to planet wheels 10 which ride on the sun wheel 11. The sun wheel 11 is driven by the motor 14 through gears 12 and 13 and transmits supplementary torque to the rolls 2 through the planet wheels; 10 and the universal joints 9.

To prevent twisting and rotation of the billet during the rolling process, the torques applied to the two driving components of the epicyclic gear system, viz. the planet carrier and the sun wheel, must be in a certain relationship and oppositely directed. For example, if the friction forces on the planet carrier and on the sun wheel are the same, the torques applied thereto should be equal to each other. If the friction forces on the planet carrier and on the sun wheel are dilferent, which is the usual case, this difference must be compensated by varying the torques accordingly.

In the embodiment with two drive motors, this compensation is obtained by the use of a current regulator (FIG. 3) inserted into the circuit of the head driving motor.

The motor 14 which drives the sun wheel draws power according to a two-stage circuit from magnetic amplifiers 15 and 16, the former being an addition amplifier, whereas the latter is a controlled rectifier.

The addition amplifier adds the following signals received by coils 17, 18, 19, and 20 respectively: a setting-up signal, a voltage negative feedback signal, a current positive feedback signal and a stabilization signal.

The rectifier amplifier sets up the rectifier voltage and provides for operation of the motor within close mechanical ratings.

Power for the head driving DC. motor 6 is supplied according to a circuit similar to that of the motor 14, from magnetic amplifiers 21 and 22, the former being a addition amplifier and the latter a rectifier.

The coils 23, 24, and 25 serve as control to control the addition amplifier 21.

The current regulating functions are fulfilled by the coils 26 and 27 of the addition magnetic amplifier 21 which is inserted in the circuit of the head driving motor 6.

The relationship between the torques applied by the head driving motor and the sun wheel driving motor is controlled in the following manner:

A voltage proportional to the current of the sun wheel driving motor 14 is taken from a resistance 28 inserted in the armature circuit of the motor.

From this voltage is deducted the controlled voltage supplied from the independent D.C. source and taken from the reference voltage potentiometer 29, whereby estimation is made of the idling losses in the sun wheel drive. Then the summary signal is divided by the voltage divider 30 which provides for estimation of the losses in the sun wheel drive under load (during rolling). The voltage taken from the voltage divider 30 is fed to the coil 26 of the addition magnetic amplifier 21. The the coil 27 of the same amplifier is fed an identical current pulse from the resistance 31 inserted in the armature circuit of the head driving motor 6. From this pulse is deducted the voltage taken from the reference voltage potentiometer 32, and the pulse is divided by the divider 33. In the addition amplifier comparison is made of the controlling ampereturns in the coils 26 and 27. The difference between the number of ampere-turns results in variation of the output voltage in the addition amplifier 21 and, consequently, in the rectifier, which, in turn, brings about variation in the speed of the head driving motor 6 with resultant change in the output torque. These variations will continue until the numbers of ampere-turns of the coils 26 and 27 become equal, i.e. until the required initial relationship is restored between the torques developed by the head driving motor and the sun wheel driving motor.

Thus, by the action of the current regulator and the devices arranged to compensate for the loss current and estimate same, the electric drives involved maintain the preset relationship of the torques applied to the sun wheel and the head, variation in the speed or load of the sun wheel driving motor automatically causing variation in the speed of the head driving motor so that said relationship is maintained within a wide range.

The current regulator is adjusted in two stages. First the idling losses are compensated for by bringing the speeds of the sun wheel driving motor 14 and the head driving motor 6 under no load to the values set up by the rheostats 34 and 35 and approximately equal to the desired rolling speed. Then the switch 36 is set in the position indicated by the dash line in FIG. 3. By the use of the reference voltage potentiometers 29 and 32 conditions are obtained where the milliammeters 37 and 38 read zero. The switch 36 is then set in the working position which results in closing the circuit between the coils of the addition amplifier 21 and the sources of the current signals.

Next a short tube is fed into the working stand and, by the use of the voltage dividers 30 and 33, the setting is obtained at which the tube is not rotating during rolling.

Theoretical estimations of the operation of said current regulator can be obtained from the rated relationship between the loads in the drives of the head and sun wheel.

In the embodiment described hereinbefore the electric drive comprises DC. motors, the functions of rectifiers and current regulators being fulfilled by magnetic amplifiers. I

If the drive is effected by the use of A.C. machines or other types of rectifiers and regulators, for example, generators, amplidynes, controlled diodes, etc., the essentials of the proposed regulator will remain unaffected. The essentials of said regulator will also remain unchanged if it be used in the power supply circuit of the sun wheel driving motor 14.

In order that rifiied portions of predetermined length may be obtained, the working stand is provided with a length sensing unit 39 (FIGS. 1, 2, and 4). The sensing unit 39 counts the pulses proportional to the length of the essentially a counter registering the pulses proportional to the head speed (such as a limit, switch, photo cell, etc.). Since the billet being rolled in the working stand is not rotating and the billet is moved axially a certain distance per revolution of the planet carrier or head, the sensing unit 38 counts the pulses proportional to the length of the ritfied portion of the billet.

On registering a certain number of pulses corresponding to the preset length of the rifiled portion, the sensing unit 39 counts the pulses proportional to the length of the words, for putting in operation the mechanism moving the wedges 4).

In order that the stand may be made in accordance with the layout illustrated in FIG. 1, the wheels 10 and 11 should be considerably spaced axially, which causes particular difficulties in the cases where a stand for rolling small-diameter billet is required.

In order to reduce the overall dimensions of the stand and to permit both motors 6 and 14 to motorize (an embodiment is possible, wherein one of the motors, say the motor 6, is permitted to motorize, while the other motor is generating), provision is made for an auxiliary epicyclic gear system 40 (FIG. 2) composed of wheels 41, 42, and 43.

Another embodiment of the stand is possible (FIG. 4) wherein the drive is effected by the use of one motor and an auxiliary epicyclic differential system 44 consisting of wheels 45, 46 and 47. In this case, the torque from the motor 48 is transmitted to the wheel of the epicyclic ditferential system.

On the driving shafts of this differential system, torques of opposite directions and different values are produced as determined by the dimensions of the differential gears.

The required values of the torques applied to the driving components of the working stand epicyclic gear system are obtained by the use of wheels 49, 50, 51 and 52 having different gear ratios.

The differential system 44 shown in FIG. 4 consists of one set of external and internal gearing. However, use may be made of any other type of differential system.

The stand of the proposed design is employed in mills for rolling rifiled tubes of considerable length from, the coil. The rolling process in the mills involved is carried out in such a manner that the tube is not rotating during rolling, being only moved axially. This permits the tube to be rolled from the coil and the rifiied tube obtained to be coiled again upon completion of the operation. This method permits the manufacturing procedure to be materially simplified and the floor space occupied by the pro duction equipment to be reduced.

The manufacturing procedure used with the mill in question is as follows:

The stock in the form of coiled thick-walled plain tubing is mounted on the drum of the uncoiler 53 (FIG. 2). The front end of the tubing is taken off the drum and fed through a Straightening and feeding device consisting of a number of pairs of driven rolls.

The straightening and feeding device (not shown in FIG. 2) uncoils the tubing and also straightens and feeds it axially.

Prior to the commencement of the rolling operation the rolls 2 are set apart so that the front end of the tubing passes freely between the rolls in order that a plain sur-. face may be obtained.

After the stock has been fed the distance necessary to obtain a plain portion of the required length, a signal is sent out for setting the rolls 2 inward.

The rolls ride on the stock 3 with a consequent embedding action on the material. Since the rolls are positioned at an angle with the aXis of rolling, the stock is continuously fed axially, the action of the rolls resulting in gradual formation of riffles.

On completion of rolling, the riflled tube is coiled by the use of the coiler 54 (FIG. 2) which is essentially a drum mounted on a support and arranged to rotate freely in an inclined plane. The formed tubing is bent and coiled around the drum of the coiler under the action of the axial thrust developed by the rolls 2 during the riffiing operation.

In the cases where the tube is formed with a predetermined length of rifiled portions, the rolls are spread apart in response to a signal from the length sensing unit 39, the subsequent axial movement of the tube being effected by the rolls of the straightening and feeding device. After the required plain portion of the tube has been passed, a signal is sent out for moving the rolls 2 inward in order to form another rifiied portion of the tube and the cycle commences all over again.

Provision is made in the mill for all the mechanisms to be controlled either manually or automatically.

The stand which constitutes the proposed invention may also be used for rolling thread on wire fed from the coil, corrugating cable stock, manufacturing plain tubing and for other applications.

What is claimed is:

1. A stand for helical rolling of billets shaped as solids of revolution, particularly for rolling rifiied tubes, comprising a driven head with a central opening allowing the free passage of a billet to be rolled; grooved rolls mounted in said head around its central opening for shaping ribs on the billet; drive means for effecting reciprocal rotation of said head and rolls; an epicyclic gear system connected to said head and rolls, and including two driving components driven by said drive means and respectively coupled to said head and rolls to drive the same and means for adjusting the torques applied to the two driving components of said epicyclic gear system such that the values of said torques are maintained in a constant relationship, while their direction is opposite.

2. A stand according to claim I, wherein said drive means comprises two DC. motors coupled respectively to the two driving components of said epicyclic gear systern, said means for adjusting the torques applied to said driving components comprising a current regulator inserted into a circuit for controlling one of said electric motors.

3. A stand according to claim 2, wherein the current regulator comprises a compensator adapted to compenr' sate for losses due to friction in the drive means, said compensator being provided with controllable power supply sources to compensate for losses when the motors are idling and voltage dividers to compensate for frictional losses when the motors are under load, adjustment of said compensator being effected by varying the voltage of said power supply sources.

4. A stand according to claim 1, wherein said drive means comprises one electric motor for imparting rotation to said two driving components of said epicyclic gear system, an epicyclic differential system driven by said motor and having two output shafts and two gear trains mounted on respective output shafts of said epicyclic differential system, said means for adjusting the values of torques applied to the driving components of said epicyclic gear system acting on said gear trains.

References Cited.

UNITED STATES PATENTS 2,385,498 9/1945 Clifford 72-97 2,430,210 11/1947 Bruegger 72-100 RICHARD J. HERBST, Primary Examiner.

U.S. Cl. X.R. 72-449 

